setup_domain_email

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Goes well beyond the readOnlyHint=false/destructiveHint=false annotations: it discloses the auth requirement, the shape of the returned DNS records (`resend.dkim_records` and their status), the constraint that from_email must belong to the domain, and the non-obvious caveat that Proof does not actually send from customer domains yet. The last point is exactly the kind of hidden behavior an agent needs.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Purpose is front-loaded in the first sentence, with return values and caveats following in a logical order and a separate access paragraph. Slightly dense, but every sentence carries information an agent can act on.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no output schema, the description correctly compensates by describing the return payload (DKIM/SPF records + status), and it covers auth. It does not address re-invocation behavior (overwrite vs. append) or error cases, which is the remaining gap for a mutation tool.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the baseline is 3, but the description adds genuine semantics: `from_email` must be on this domain, is stored as the preferred sender, and is currently unused. The only gap is that `id` is still just 'Domain ID' with no clarification of provenance (e.g. from add_domain/list_domains).

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb+resource ('Register a verified domain with Proof's email provider (Resend) for sending') and immediately scopes the outcome to DKIM/SPF record provisioning. An agent can distinguish this from add_domain/verify_domain/start_domain_email_verification without opening any schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The ACCESS block gives real prerequisites (PROOF_API_KEY or the start_login session flow), which is useful. However it never states when to choose this tool over the many sibling flows (start_domain_email_verification, confirm_domain_email_code, check_domain_email_status, resend_domain_email), so alternative selection is left to inference.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.